A Brief History of Time
The idea of soaring can also explain why there are so many substances in the universe. In the universe we can observe, there are about 65438+ billion (1 followed by 80 zeros) particles. Where did they come from? The answer is that in quantum theory, particles can be generated from energy in the form of particle/antiparticle pairs. But this only raises the question of where the energy comes from. The answer is that the total energy of the universe is just zero. The matter of the universe consists of positive energy; However, all substances are attracted by gravity. Two substances that are close together have less energy than two substances that are far apart, because you have to consume energy to overcome the attraction that pulls them together and separates them. Therefore, in a sense, the gravitational field has negative energy. Under the condition that the universe is generally consistent in space, people can prove that this negative gravitational energy just offsets the positive energy represented by matter, so the total energy of the universe is zero.
Twice zero or zero. In this way, the universe can double its positive matter energy and negative gravitational energy without destroying the conservation of energy. This did not happen when the universe was expanding normally. At this time, the universe becomes larger and the energy density of matter decreases. However, this did happen during the boom. Because when the universe expands, the energy density of the supercooled state remains the same: when the volume of the universe doubles, both the positive material energy and the negative gravitational energy double, and the total energy remains zero. In the skyrocketing stage, the size of the universe has increased by a very large factor. In this way, the total energy available for making particles becomes very large. As Gus said: "It is said that there is no free lunch in the world, but the universe is the most thorough free lunch."
From Hawking's The Universe in the Shell
The ups and downs in a vacuum will make the movie world appear a bubble from scratch. The film forms the surface of the bubble, while the interior is a high-dimensional space. People in movies, that is, people on the surface of bubbles (such as us) will think that the universe is expanding. It's like drawing a galaxy on the surface of a balloon, but blowing it up, the galaxies will leave each other, but none of them will be regarded as the center of expansion. Let's hope no one deflates the bubble with the needle of the universe. With the expansion of the membrane, the volume of the internal high-dimensional space will increase. Finally, there is an extremely huge bubble surrounded by the membrane in which we live. The film, that is, the substance on the surface of the bubble, will determine the gravitational field inside the bubble.
The inside of the membrane universe is a high-dimensional space, and the outside of the membrane universe is absolutely empty, even empty space.